The present invention relates to a recuperator and turbine support adapter for a recuperated gas turbine engine, and more specifically to a recuperator and turbine support adapter with a thermal spring for attaching a recuperator to the engine.
Gas turbine engines often may use a heat exchanger or recuperator to increase operational efficiency by extracting heat from the exhaust gas in order to preheat the air entering the combustor. Recuperators are specifically designed to operate in extreme environments. The hot-pass side of the recuperator is subjected to pressurized engine exhaust gas in excess of 1000° F. Meanwhile, the cold-pass side of the recuperator receives compressed ambient air at temperatures which may exceed 600° F. The potentially destructive combination of high pressure differentials, high thermal differentials, and corrosive combustion by-products is amplified by thermal cycling and startup/shutdown cycles. Thus, the recuperator must be extremely rugged, while being flexible to accommodate thermal growth.
U.S. Pat. No. 4,474,000 discloses a design for mounting a recuperator to a gas turbine engine. The mounting system has flexible metal seal elements where the recuperator is joined to the engine that prevent compressor discharge air from escaping into the exhaust stream. The flexible metal seals also allow for thermal growth of the recuperator. The flexible metal seals, however, are limited by the thermal expansion capabilities of the materials used to make the seals. Therefore, over time and/or under extreme conditions, leaks and damage may occur.
U.S. Pat. No. 6,601,392 discloses an apparatus having spring supports for supporting a recuperator of a microturbine engine. The springs of the apparatus allow for thermal expansion of the turbine with a minimum amount of force being applied to the turbine. The apparatus is limited to use with microturbine engines where the recuperator is mounted in a vertical position above the turbine. The springs of the apparatus do not assist the recuperator in relieving internal thermal stresses within the recuperator.
As can be seen, there is a need for a recuperator and turbine support adapter for a recuperated gas turbine engine that can withstand exposure to extreme thermal and pressure gradients.